


Adventure Time: World Chaos

by RealDone_Universe



Category: Adventure Time, Fairy Tail
Genre: F/M
Language: English
Status: In-Progress
Published: 2016-04-08
Updated: 2016-04-08
Packaged: 2018-06-01 01:36:53
Rating: Teen And Up Audiences
Warnings: Graphic Depictions Of Violence
Chapters: 2
Words: 9,000
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/6495649
Author URL: https://archiveofourown.org/users/RealDone_Universe/pseuds/RealDone_Universe
Summary: <blockquote class="userstuff">
              <p>[Post Tartaros Arc] Finn's world changes as an apocalyptic event ravages earth, corrupting all life and leaving him as the only pure human being. With his best friend, Jake the dog, the adventurer goes on a mission with the Fairy Tail wizards to save the world and liberate Ooo from a horde of demons.</p>
            </blockquote>





	1. Prologue

**PROLOGUE**

SKIDDING ALONG the grass, Finn panted and smirked as Jake, the Afghan Shepherd, huffed excitedly, seemingly mocking him. Brandishing his sword, Billy chuckled, pacing around the teen in a forest, watching him as he got to his feet and held his blade at his side.

"Y'know, if there were a lesson on getting your butt kicked, you'd be an A-student." Billy smirked.

"If there was such a lesson, I'd be an F-student." Finn took his stance.

"But you already _are_ an F-student."

"Never!"

Finn swung at Billy who sidestepped, quickly dodging the attack and locked blades with him. Billy kicked him back and swiped at his gut, nearly cutting him as he jumped back. Finn stabbed at Billy and he sidestepped, attacking again with a slash to his midsection, colliding with his blade as the man blocked.

"Too slow."

Billy elbowed Finn, knocking him down and he quickly rolled to his feet, chucking grass in his face. Using the distraction, Finn kicked him in the knee and slashed at him as he went down, hitting his blade as he blocked. Finn gave him kicked him and stabbed at the ground near his head, pinning him down.

"You were saying?" Finn smirked.

"Kinda played it dirty, didn't ya?" Billy raised his brow.

"Learned from the best; 'when outmatched, cheat'."

"Pretty sure I didn't teach ya that."

"Yeah, I winged it." Finn twirled his sword.

"Guess I'll bump you up to a B."

Finn snorted. "That was totally an A." Stepping back, he helped him up and sheathed his sword on his back, turning to Jake who walked toward him. Patting him on the head, he looked around and saw a redheaded girl move up to him with a wide smile on her face.

"Hey, Finn."

"Phoebe, what're you doing here?" Finn turned to her.

"Hey, Billy." Phoebe waved at him then turned back to him. "We've got a job to do."

"Oh, right." He shook his head. "Billy, thanks for the session, I've gotta get going. Come on, Jake."

"Wait, Finn, I've gotta give you something." Billy walked over to his bag that was lain on the ground, fishing out an thick, old hardcover book with a sword and a skull on the front."

"The Enchiridion?" Finn's face lit up a he received it. "No way!"

"Yeah, I think you've trained hard enough and you've earned it." Billy drew a golden sword from his back.

"Wow, this is so cool." Finn eyed the book as he held it up, nearly drooling as he watched in awe.

"Wait, I thought you said he had a few months to go before he was done with his training." Phoebe's brows stitched.

"Well, that's because I'm done training him; he'll have to learn the rest on his own from now on." Billy gave Finn the blade.

"Whoa, the Golden Sea sword." Finn looked at the sword closely, smirking then jerked back as it hit him. "Wait, you're done training me?"

"Yes."

"But, why?"

"I don't have a choice, Finn; you wouldn't understand." Billy sighed. "You'll have to continue training on your own."

"But there's so much I don't know. Why're you leaving?" Finn sheathed the blade..

"There's something I need to do and I might not come back." Billy placed a hand on his shoulder. "I'm sorry, I can't tell you anything; if I did, you'd come along and get yourself killed."

"What's going on? Lemme help you." Finn stood in his way.

"I'm sorry, Finn." Billy picked up his bag. "This is goodbye. I hope I can see you again, but I'm not so sure."

"No, Billy I can help."

"I'm sorry, Finn, you can't." He began to leave. "You take care of yourself, you hear."

"Y-yeah." Finn's expression fell.

"Phoebe, you make sure he doesn't get into any trouble!"

"Hey!" Finn growled and Billy laughed, waving as he walked away. Finn huffed then gave a confident grin, calling after him. "When you come back, I'm gonna fight you again! You'll see how powerful I'll be!"

"Sure thing, kid."

Phoebe's brows furrowed as she watched Finn's smile die down as he looked at the Enchiridion solemnly. "Are you okay?"

"Yeah." He nodded. "He'll be back." He stuffed the book in his bag. "C'mon, lemme just drop my stuff back home and we'll get going."

OPENING THE DOOR, Finn entered the foyer of his house, walking past the living room where his parents were, moving up to the staircase when he overheard them speaking. "So, what're we going to do now?" His mom's voice came.

"I don't know." His dad huffed. "We could sell some furniture – maybe the cattle."

"Even if we sold everything, we wouldn't be able to raise half of the money to pay back Big D."

"Guess we'll have to give up the house then."

"Martin, we can't give this place up! You've worked too hard for this and I can't start moving again; you'll need to find a way raise the money somehow."

"He's only given me a week."

"Can't you do something to get more time?."

"Well, I don't know what I'm going to do …"

Finn sifted his mind and went up to his room, removing his bag and placing his sword beside his bed. Moving over to grab his hoody, he stopped and looked at his desk, pulling out a metal box from the drawer and opening it. He frowned as he saw a few notes and some coins inside, huffing and closing it.

* * *

SQUINTING AT the harsh sunlight, an elderly lady opened her old creaking door, seeing Finn and Phoebe standing in her driveway with shopping bags in hand. Giving them a warm smile, she invited them in, leaving them in her small living room as she went upstairs.

"You think Ms Abadeer's gonna pay us well this time?" Phoebe turned to Finn.

"We're just picking up meds, so I dunno." He shrugged.

The woman returned, her step slow, though spry for her age. "Oh, thank you very much, you've helped me greatly." She sat across from them.

"Well, here's the stuff you wanted." Finn placed the shopping bags on the coffee table.

"Yes, thank you … but …" Ms Abadeer frowned. "I won't be needing that anymore."

"But why? We just bought them." Phoebe raised her brow then read her expression. "Is something wrong?"

"No, it's nothing you should worry about …" The lady put on a smile. "Finn, I want you to have something." She moved over to a desk nearby, picking up an amulet and giving it to him.

"Uh, what's this for?"

"Well, for your services of course."

"You're not gonna pay us?" Phoebe frowned slightly

"I'm sorry; I've got nothing else I can give you." Ms Abadeer shrugged.

"After sending us on all those errands, you can't give us any money? All you've done is given us is pocket change and now you're not even gonna give us anything?" Phoebe growled.

"Phoebe, calm down." Finn frowned.

"Whatever." Phoebe scoffed and headed for the door. "C'mon, Finn." She stormed out.

Finn looked at the door and rose to his feet; heading to it when he stopped and turned to Ms Abadeer. "Those weren't for you, were they?"

She smiled wistfully. "You take care, Finn." Finn left the room and she sat back, looking at a cracked crown on a shelf across from her.

* * *

FINN TOSSED his bag on the floor and plopped on his bed, looking around his room as he pushed his hood back and took a deep breath. Moving up to his desk, past Jake, he pulled out the pencil case and opened it, stuffing it with money from the job he'd just finished.

It was nowhere near enough, but he felt he'd need to help his parents somehow; every penny counted. Moving down to the living room, he turned to the kitchen, seeing his them talking at the table. He walked up to them, followed closely by Jake when he felt the ground shudder.

"What was that?" His mom shot up.

Adam turned to the window and jerked back, his eyes widened in horror. "Oh my God."

Finn squinted as he saw several mushroom explosions rise up in the distance, its boom reverberating and shattering the windows as clouds of debris quickly engulfed the street raced toward them. It broke into the room and enveloped it, sending them flying back.

Finn pried his eyes open, slowly moving his arm as he realized he was floating in mid-air. Yellow energy exuded from his body, suspending him as the world around him slowed, almost frozen in motion. Turning to his right, he saw Jake floating the same way he was, gasping as his parents hurled through the air. The Enchiridion flew out of his bag and landed in his hands, a bright light exploding out of it and blinding him.

"What the …?"

* * *

FINN GASPED as he scrambled around, his heart racing as fear enveloped him and he hyperventilated. His vision came slowly, the dying bright light giving way to a forest he sat in. Taking in his environment, he slowly calmed himself and struggled to his feet, his body feeling numb as he looked around.

A rustling came from the bushes and he jumped back, reaching for his sword as he awaited what approached. A dog stepped out of it, an Afghan Shepherd standing on its hind legs with longer upper limbs shaped like arms. It's coat was brown with a path of white on its head and going down its back like spikes.

"Whoa!" Finn backed away in surprise. "What-what are you?"

"Finn! I was looking for you –," The dog gasped, looking at his paws. "I can talk?"

"What are you?" Finn frowned.

"You don't recognise me? Whoa, I'll take long to get used to this." The dog chuckled. "Wait – focus! Finn, it's me, Jake!"

"Jake? B-but how?" Finn sheathed his sword. "You're a dog."

"I don't know, but I can talk somehow – whoa, somehow … somehow … somehow? … Somehow!" Jake howled. "Whoa, sorry, I'm a little psyched." He wagged his tail.

"What happened?" Finn looked around. "Where's my house? Where're my parents?"

"I dunno, I just woke up here and tried to find you." Jake sniffed around. "My senses are heightened too. And I thought my sense of smell was high before."

Finn sifted his mind and frowned. "C'mon … Jake." He huffed. "Let's try to find out what's going on here."

Manoeuvring through the forest, the two came across a village they seemed to be on the outskirts of. Entering the area, Finn and Jake watched in shock and confusion as deformed people walked around them. Each of them had green or blue skin tones, most clad in tattered clothes and others clad in western clothing.

Frowning, Finn moved up to a woman. "Excuse me."

"Yes?" She squinted at him.

"Um, ma'am, could you tell us where we are?"

"Oh, well you're in the Bad Lands, young child." She smiled.

"The … Bad Lands?"

"Yes, this town is Cream Crop. You've never been around here before, boy?" Her brow curved.

Frowning, Finn stepped back and tried to piece together what she'd said. "No." He moved up to a man seated on a bench. "Excuse me, sir, what country are we in?"

"Why, this is the Land of Ooo, wild stranger!" The man adjusted his hat. "Where ya from?"

"USA." Finn frowned.

"What's that?" The man's brows stitched.

Finn jerked back and looked around, seeing that Jake shared his surprise as he looked at the people around him. "What's going on here?" Finn's mouth fell agape.

* * *

MONTHS LATER, Finn and Jack manoeuvred through the cluster of people as they walked up to the counter. Banging his fist on it, Finn smirked as the bartender came over and fished out a bag of coins, dangling it in front of him.

"C'mon, Nick, I did the job; they won't cause trouble for you again." Finn sat down, his smirk widening. "You don't trust me?"

"Yeah, just playing around." Nick tossed the bag to him.

Finn opened the satchel, counting the money. "This's a little more than you said."

"Well, I just appreciate what you've done for us." Nick poured him a beer. "Since you came nearly a year ago, things have changed a lot in Ooo. You've taken down monsters, bandits; many things we've been plagued with for years."

"I've just did what I had to." He pushed the glass back.

"Still ain't taking booze, huh?"

"I'm seventeen; it's illegal."

"Well, I don't care if it is; nobody does, so it's okay really."

"I've got values I live by, following law's one of them."

"Kinda one of the things why some people don't trust you." Nick frowned. "There're a lot of things you could do that you don't. You could have people pay you lots of money, use your power to get what you want; you don't drink – it raises suspicion; you can't be that perfect. I trust you, but I have wondered like, why do you accept simple jobs like the one I gave you. You've fought monsters, demons, but you got hired to take down a bunch of thugs, why is that?"

"There're some things that are more important than money." Finn smirked.

"If you say so." Nick chuckled. "Hey, I've got another job for ya."

"What is it?" Jake took a seat.

"Came from a stranger who wants you to destroy an underground demon kingdom near the Ice Kingdom whose hordes have been terrorizing neighbouring villages."

"The Ice Kingdom? Oh, man." Jake groaned. "Can't we just avoid the Ice King for once?"

"I discovered a route around the kingdom recently; we're not gonna bump into him this time." Finn turned to him.

"The woman gave me a map and said that she'll pay you handsomely if you take down the demons or find a way of sealing them down there." Nick moved over to fill a customer's glass.

"Huh, taking on more demons – that sounds awesome." Finn grinned.

"I'm sure an adventurer like yourself will find this job easy." Nick fished out a map from under the counter, sliding it to him. "He said you should go to the address on the bottom right to claim your payment."

Reading the map, Finn grinned. "You can count on us!" He pocketed the map. "Thanks, Nick."

"Sure, come again." Nick moved over to another customer.

Heading out of the bar, the two walked down the sidewalk as Finn read the map closely, cementing a route in his mind. Pocketing it, he slid the upper cover of his gauntlets, looking at what lay within and tapped on the pavement, adjusting the straps of his backpack.

"This is gonna be awesome!" Jake shot his fist up.

"Yeah, haven't had a mission this big in a while." Finn cracked his knuckles. "Got a chance to test my skill and find new weapons."

"Well, what're we waiting for? Let's get moving!" Jake ran onward and Finn followed him.

* * *

BREATHING HEAVILY, Finn shielded his face as the wind swept past and sand stung his eyes. Jake squinted and looked around the desert they stood in, turning around to see vast glacial terrain peaking in the distance. Huffing the canine trod on as he bit a flea off his arm and traversed the sea of sand.

"Been at this for months and I still can't get used to seeing a hot desert next to a glacier world." Jake sighed.

"Well, we just have to." Finn shrugged.

"How far are we?" Jake turned to him.

Finn pulled out the map. "We should be right next to." He stopped quickly. "… it."

A large humanoid demon stood before them in front of a massive crater, reaching around eight feet tall and wielding two swords. With a lean build, red, scaly skin, horns lining its head, brown tattered trousers and boots, the beast snorted and walked toward them, putting a grin on Finn's face.

"Alright, let's do this!" Finn ran toward him.

Reaching behind him, he unzipped his backpack with both hands and unsheathed a large, red broadsword, Bloodsoak, from its abyssal depths, running alongside Jake whose forearms enlarged. The demon stabbed at Finn and he jumped out of the way, letting him impale the sand and sliced his arm.

The demon backed up and swung his blades at him twice, missing his head as he rolled out of the way and slashed at his boot. The beast sidestepped and Jake grabbed his leg, his arm outstretching at over a metre as he swung it around and tossed it away.

The monster flipped over and skidded to a stop, throwing his swords at the two as he stood up. Finn flipped out of the way and Jake ducked under a blade as the demon magically summoned weapons he sent their way. Finn slid down the metal plates of his shin-guards, revealing crystals underneath and jumped into the air, spinning around as he slashed at the beast. The creature tried to block with his forearm and Finn sliced it off, rolling to his feet as it writhed in pain. The appendage grew back.

"Oh, crap!" Fear dilated Finn's eyes.

The beast punched at Finn and he ran out of the way, swinging its arms wildly as it pursued him. Finn jumped back and the monster smacked him aside, flinging him back as he spat blood. The demon summoned a sword and slashed at him, meeting steal as he quickly got up and shielded himself with his blade.

Jake punched the monster in the ribs, sending it skidding back and Fin launched into the air, stabbing its forearm and leapt off it, landing behind him. Jake upper-cutted the beast, making it stagger to Finn who slashed its chest, moving it over to receive a heavy left hook, taking it to get impaled in the chest then decapitated it. Finn shook blood off the sword and sheathed it in his back, zipping it shut and slid the plates of his boots back down.

"Man, that was tough." Finn panted. "C'mon, Jake, let's get –,"

"Shh!" Jake grabbed him with an enlarged arm.

"What're you –,"

Jake launched high up into the air and landed far from the ditch, setting Finn on the ground beside him. Hushing the teen, the dog looked at the chasm again, sniffing around as he stood up and frowned.

"There're several demons back there." Jake turned to him.

"Well, duh, it's a demon kingdom." Finn rose to his feet.

"No, they were crowded around the entrance. They were waiting for us."

"Who tipped 'em off?"

"I dunno, but we have to be careful."

"So, how're we gonna get in?" Finn looked at the ditch.

"We don't have to. Weren't we told to seal 'em in?" Jake smirked.

"Our job just got a whole lot easier." Finn grinned.

Jake grabbed Finn and jumped back to the crater, setting him down and enlarged his arms, making them massive. He punched the rims of the chasm, sending rocks plummeting into the depths as demons tried to climb out of it. Shrinking his appendages, he and Finn chuckled, high fiving each other as the pit collapsed.

"That was awesome! Maybe we can –,"

"Wait a minute." Jake frowned, his ears twitching as he turned to the pit. "I think I heard something."

"What?" Finn's brow curved.

Jake pressed his ear against the ground near the pit. "Oh no!"

"What is it?" Finn turned to him.

"Follow me."

Pushing rocks aside, Jake dove into the chasm, followed by Finn who huffed before jumping after him. The depths engulfed them in darkness as they descended, seeing a black, thick substance lining the walls of the ditch as they went down further and further.

* * *

FIRE ROSE upward as lava veined the ashen earth and spread out into pools and lakes. The air was foul and thick with soot and smoke, the roof of the massive underground cave darkening the realm. Several demons ranging from the height of tall trees and small lizards roamed the area.

Sand and rocks fell from the massive hole in the ceiling, giving way for Jake, Finn and demons that fell to the ground below. Unveiling the crystals in his boots, Jake grabbed Finn and shot through the air, crashing near a rock nearby where he slid his shin-guards back down. He quickly rose to his feet, moving up to some dry grass as he studied the area when he heard the dog suffocate.

"Jake!"

Finn ran up to the canine's side as Jake coughed and gasped for air as he writhed on the hot ground. Reaching into his backpack, he fished out a neck chain with a stone amulet he draped over him. Stepping back, he sighed in relief as a blue energy exuded from the necklace and enveloped his body.

Jake gasped heavily and panted. "Thanks, Finn."

"No problem, buddy." Finn crouched. "Now, what'd you hear?"

"I heard a girl screaming."

"Who?"

"I don't know, but it sounded very familiar." Jake got to his feet. "It came from … there." He pointed forward.

Turning around, Finn's eyes dilated in surprise as he saw a massive edifice at the centre of the area. Made of the black substance that was splattered all over the place, the structure rose out of the ground and into the ceiling, its walls spiking out like a grotesque tree trunk whose sides had windows littered around.

"Must be the palace." Finn frowned.

"Yeah." Jake walked up to him.

"How're we supposed to seal this place off anyway?" Finn looked around. "There're a lotta demons here and I bet burying them won't work unless we destroyed the entire ceiling." He looked up. "I don't think we'd be fast enough."

"Guess we'll just have to take 'em out." Jake shrugged.

"More than obliged." Finn grinned and unsheathed Bloodsoak from his backpack. "But first, let's sneak up to the palace and find out who's in there."

"Yeah." Jake smirked.

Moving across the area, the two manoeuvred through the demons that dwelled there, hiding behind grass and rocks as they made their way to the centre of the realm. Reaching up to the back of the edifice as the front had wraiths manning it, Finn held his arm up and shot out a tethered claw from his gauntlet with spikes outstretching like knuckles, latching onto a window and pulled himself up, holding Jake at his side.

* * *

CLIMBING THROUGH a window, Finn and Jake jumped into a kitchen, jumping back in horror as they looked around. Blood splattered on the floor as human corpses hung off hooks like slaughtered animals in the filthy butchery. Covering their mouths from the foul stench, the duo quickly ran out of the room.

Entering the hallway, the two hunched over and panted, shaking their heads as they took in what they saw. Pushing his scarf down, Finn vomited on the floor, shivering as he stepped back and wiped his mouth, feeling weak-kneed.

"What the hell was that!?" Jake turned to Finn.

"Hell?" He retched and puked again.

"Hey, you! What're you doing here?" A voice came.

Two demons from opposite ends of the hall ran toward them, each wielding massive swords. Grabbing the monster to his right, Jake grazed it on the ceiling and threw it over to Finn who drew out Bloodsoak, spearing it through the two beasts, skewering them and dislodged the blade, shaking the blood off.

"Let's keep moving." Finn sheathed the blade.

Jake looked around and closed his eyes, his ears twitching. "I heard her again."

"Lead the way."

Following the dog, the teen looked around as they traversed the halls, hiding in closets as they came across demons patrolling the area. After searching for hours, they opened a door and came up to a podium overlooking a massive room similar to that of a concert hall with a large throne on the stage whose backrest reached into the ceiling. Finn frowned deeply as he saw a girl seated in it, shooting a grappling hook to the ceiling and using it to swing down to her.

Landing before the throne, Finn rose to his feet as he walked toward the girl, his eyes trailing her in horror. A girl sat on the cathedra, her body covered by the black substance that wrapped around her legs, thighs, arms and neck, binding her. Her skin had an orange tint, her crimson red hair splayed over her shoulders as her head swung back and sweat beaded all over her as she panted and screamed.

"Phoebe?" Finn ran up to her.

She quickly turned to him, her completely black eyes making him jerk back. "… Finn?" Her brows stitched. "Finn is that you? How?"

"Phoebe! I've been looking for you for so long." He ran toward her. "I –,"

"No, don't … please."

"Why? I need to save you –,"

"Finn, don't, you'll end up dead if you do." Fear exuded in her expression.

"What's going on?" Finn frowned.

She screamed and grimaced as the black substance slithered around her, making her whimper. Finn ran toward her and she shook her head. "No, please!"

"Phoebe, that thing's hurting you!"

"Phoebe?" Jake jumped onto the stage, his eyes dilated in shock. "Phoebe! What happened to you!?"

"Please, you need to get out of here, it's not safe." She panted.

"I can't leave you here!" Finn walked up to her.

"Finn, you need to understand; don't try to help me!"

"Why?" His brows furrowed.

Phoebe winced. "It's been four hundred years since I last saw you and I woke up in a forest looking like this."

"Four hundred years? How're you still alive?" Finn backed up.

"I don't know, but I've been alive for that long and I haven't aged ever since." She turned to him. "I wandered around looking for my parents when the demons captured me and brought me here. They said I was the Flame Queen and put me here on this throne to … rule them." She began to tear up. "It was for their amusement. This thing has been torturing me since then and they've watched me day after day as if I were some kind of opera to them. When I didn't cry enough, they'd whip me … strip me." Tears flowed. "And I didn't die. All I wanted was to die, but I was still alive for them to torture me and all this time, they've kept me in this chair."

Finn frowned, anger raging in him as he clenched his fist till his knuckles whitened. "Then why can't I help you."

"Because they told me that I was the only one who could keep them here. If I'm gone, they'll just go out and search for another Queen to torture and I can't let this happen to anyone else. If I escaped, I'd have endangered you." She panted. "I'm too weak to run now."

"Phoebe, let me help you." Finn walked up to her. "I'm not leaving you here."

"But the demons –,"

The twin doors of the hall opened and demons flooded in – each of them armoured and armed with blades. Jake jumped into the fray and battled the horde, his enlarging arms tossing them around like ragdolls. Finn grabbed Phoebe and pulled her off the chair, ripping the substance off her body and set her on the floor. Removing his hoody, he draped it over her and looked at her, seeing the marks the chair left on her.

"Finn."

The room quaked and the demons turned to the centre stage, growling as they saw the throne empty. Abrupt chaos broke out as the beasts ran out of the room and flew out, the walls cracking as tremors spread all around. Shielding her from oncoming debris, Finn looked into Phoebe's eyes, seeing the black receded, revealing the fiery orange in them as fear steaming in her tears.

"Finn, w –,"

"I'm not leaving you, Phoebe; never again."

She smiled warmly, letting him carry her as he clenched his fist and shot a grappling hook from his gauntlet at the ceiling, pulling them up into a crack that spread across the roof. Kicking a demon back, Jake ran up to the stage and jumped up, diving through the hole.

* * *

ONE YEAR LATER. Finn crouched behind a blockade, glancing at Jake who sat across from him and Phoebe was at his right side, shifting as he turned to a woman who crawled up to him. She had pink hair with cotton-like strands interweaved, her skin having a pink tint and matching her shirt, pants and boots.

Bonnie went on her comm. unit. "Are the Banana Soldiers in position?"

"Yes, Princess." A soldier responded.

"Good, let's move in." She went off comm.

* * *

**AUTHOR'S NOTE: Welcome to the Universe! Hope you enjoyed the chapter. This book takes place in an AU comprised of different versions of the show's cast with some changes of our own. Those who haven't watched Adventure Time don't necessarily have to be familiar with the lore because we follow it loosely.**

**This book will be a crossover with Fairy Tail, but this chapter had to cover our changes to the lore of the show and establish our setting. We're – hopefully – using a more realistic and darker tone with Adventure time in order for it to work with Fairy Tail that you'll hopefully enjoy. Finn and Phoebe are eighteen in our continuity and Phoebe is human originally, having being changed by the events about halfway in this chapter. Our knowledge of the Adventure Time lore is fairly limited, so we'd be grateful if those of you that know more could help us with some ideas that we could possibly integrate into the story. Thanks for reading.**


	2. Heroes and Mages

**HEROES AND MAGES**

THE GLARING sunlight dissolved into a collage of pink and white dominating an assortment of colours as Bonnie, Finn and Jake walked onto the balcony of the Candy Kingdom palace. Looking over her citizens with joy welling in her, Bonnie moved up to the railing and waved at the people, soliciting applause from them as they saw her. The Candy people had humanoid builds, their skin colours ranging from blue, brown, orange, green, pink, purple, white and red with hair infused with strands of different confectionary substances.

Clearing her throat, Bonnie spoke with a strong voice. "Candy People, for over a year, our kingdom was ravaged by hordes of demons that plundered our land. Many lives were lost, children were killed and homes were destroyed, but now we have our city back. Now we have taken back what we lost thanks to Finn the human." The people erupted in excitement as she gestured to him. "With his valiant heroism and his best friend, Jake the Dog, Finn drove away the demons and saved our kingdom. Finn, Jake, please step forward." The two stepped up to her and she walked toward them. "I would like to award you for your bravery and for saving our kingdom." She drew out two medals and draped one over Jake. She chuckled as the dog wagged his tail and she moved up to Finn, placing the other on him and stepped back. "Let's hear it for Finn and Jake, the heroes of Ooo."

"Wow." Jake laughed slightly and eyed the souvenir. "This is so cool."

Finn grinned as the citizens cheered for them. Looking at Jake who eyed his medal with glee, he moved up to the guardrail and looked to the people. "Candy Kingdom, for years I –,"

"No, stop, Finn." Bonnie pulled him back. "Only I give speeches, not-not you."

"…Okay?" He raised his brow and she grinned.

* * *

BONNIE'S EYES thinned as she leaned over her microscope in her messy lab filled with various contraptions that were damaged and rusted with age. The lights came on and she hissed at its harshness. She turned and saw Finn, Jake and Phoebe standing in the doorway.

"Oh, hey guys; didn't expect you to come so quickly." She chuckled slightly.

"Well, you called us here, so what's going on, PB?" He walked toward her.

"Oh, please, just call me, Bonnie."

"PB works." Finn looked around the room. "What're you doing here?" He sniffed. "And what's that smell?"

"It's like something died in here." Phoebe covered her mouth.

Moving around the room, Jake searched and walked up to Bonnie's workstation. He looked at what lay in a large bath within and jerked back as a demon's corpse was in there. "Whoa, what's that doing here? That's seriously messed up!"

"Oh, that's what I wanted to talk to you about actually." Bonnie turned to Finn. "I've been studying the corpses of the demons you'd killed and –,"

The demon suddenly shot up and clawed at the edge of the bath with a low, moaning roar. "Oh man, it's alive!" Finn drew his sword when Bonnie suddenly laughed and drew confused looks from the three who eyed in her with curiosity. Pressing a button on the edge of the table, she stepped back and gestured as the corpse lay back down. "Hey, what the hell?"

"Sorry, I was just playing a prank on you." She wiped a tear from her eye.

"That's not funny, Bonnie." Phoebe frowned. "I was tortured by those things for _years_."

"Come on, it's April Fools, remember?"

"An April Fools prank is a whoopee cushion or a pie in the face; this is just wrong." Jake poked at the corpse.

"Really?" Bonnie's laugh died down and Finn nodded at her with a frown. "Oh, okay then, heh." She scratched her head and cleared her throat. "Anyway, I've been doing some autopsies on some of the demons you'd killed – obviously, not this one." She pressed a button on the table, closing the tub. "And what I found was surprising." She gestured to a screen that slid down. On it were molecules moving in an X-Ray of a demon. "There were trace elements of magic similar to the Enchiridion on the corpses."

"What?" Finn's brow rose.

"How's that possible?" Jake turned to the monitor.

"I dunno, but I've scanned the Enchiridion before –," Bonnie winced as Finn frowned at her. "Sorry, I didn't ask, but anyway; I'd scanned the book before and the magic is a close match."

"Do you think the demons came from the book?" Phoebe's brows crossed as she turned to Finn.

"No, it's not possible; the Enchiridion's a hero's book – it can't be evil." Finn frowned.

"But we don't really know anything about it –,"

"It's not evil." He reiterated.

"So, I was thinking I could possibly look through the book and –,"

"No, we don't wanna attract the Lich by opening it." Finn interrupted Bonnie. "We just need to keep studying the corpses until we find something else."

"Okay, suit yourself." Bonnie shrugged.

Finn glanced behind him as Jake and Phoebe headed for the door. Leaning against the table, he smiled at Bonnie as she moved around, gaining a glance from her. "What?" She moved to a computer.

"Well, I wanna help, so, what're you gonna do?" He smirked.

"I'm not gonna be doing anything right now; I need to take a shower first – kinda sweaty."

"I can help with that." He chipped.

"No, Finn, I'm not gonna have sex with an adolescent." She headed out of the lab.

"Hey, I'm nineteen." He followed her as she entered the hall. "And, I'm not trying to … sleep with you; I just wanna help with whatever … you wanna do."

She stopped and turned to him with an unconvinced look. "What could you help me with in the shower that wouldn't be sexual?"

He glanced around and tapped his fingers. "Washing your back?"

"Go home, Finn."

"Fine." He stooped over.

* * *

FINGERS BLAZED over the keyboard as Bonnie's eyes trailed down the screen that lit the dim room. Looking at the time on the taskbar, she huffed and rubbed her nose underneath her glasses. She clicked on the screen, bringing up an application and cleared her throat.

"Bonnie's log, Demon Corpse Study: it's 11:45 pm, April 8th 2016. Autopsy and high-res molecular scans have proven fruitless. Corpses have reached dry decay and fresh samples are decomposing as well." She huffed. "I need more varied specimen to find more than the magic particles." She minimized the program and brought up the world map, moving up to Eurostralia and zoomed in on Ooo. She panned upward and looked at Fiore. "Time to give Finn some help."

* * *

"STOP THERE, evildoer!" Finn stepped on the hood of a car, pointing his sword forward as he took a heroic stance.

"Dude, it's gonna get away." Jake ran past him as he manoeuvred through the packed streets of the Candy Kingdom.

"You've gotta stop being so dramatic all the time." Phoebe flew past him, propelling herself with fire from her hands.

"But bad guys need to know a hero is taking them down." Finn shot a grappling hook at a building from his gauntlet and ran on the roof. He looked at the road ahead as a black, scaled, humanoid demon sprinted onward.

"You're already a hero; people know that." Phoebe smiled.

"It's not about fame." He winced as she raised her brow. "Okay, maybe a little, but it's about letting the bad guys know that they're not gonna get away with anything."

"Well, let's stop them then!" Jake thrust his hand onward, his arm enlarging and he moved to grab the demon. "Now I've got ya!"

"Fire Dragon Roar!" A loud voice came and a fireball consumed the demon, causing it to writhe as it lashed out and fell on the road.

"What the?" Finn skidded to a stop and jumped down to the sidewalk.

"Well, that was close; that demon could've hurt people." A pink-haired man clad in a hooded black coat, white trousers and boots with his left sleeve torn and bandages wrapped around his arm. With a wide grin, he looked around and began to drool.

"Oh wow, the city's made of candy!" A blue cat with white wings flew around in the air.

"Stop it, Happy, we're here on a mission, not to –," A redheaded girl clad in armour with a sword sheathed on her back looked around as her mouth fell agape. "It _is_ made of candy."

"I thought you said we should focus on the mission." Crossing his arms, a raven-haired man clad in a white jacket navy blue shirt, black jeans and shoes frowned.

"Uh, Natsu, what're you doing?" A blonde girl clad in a vest and skirt raised her brow with unease as the man walked toward a building.

Punching a hole in the wall, Natsu grabbed a chunk of it and bit into it. "Wow, it is Candy!"

"Hey, what're you doing!?" Finn frowned.

"What? I'm just gonna eat this building." Natsu spoke with his mouth full and swallowed. "The city's made of candy, right? Just having a snack."

"Never!" Finn yelled as he ran up to him and swung his blade.

Catching the blade quickly, the man jerked back and blinked in surprise. "Whoa, you could hurt someone with that."

"I'm not gonna let you eat this city!" Finn punched Natsu, knocking him off his feet.

Wiping spit off his lip, Natsu smirked. "Oh, I'm fired up now!" Slamming his fist in the palm of his hand, he charged fire through his arms and got to his feet.

Natsu threw three fiery punches at Finn, aimed at his head. Dodging the strikes, Finn kicked him in the gut, causing him to skid back against the ground and he lunged at him. Finn drove his sword at him and Natsu dodged, giving him an uppercut that sent him flying back.

"It's on now!" Phoebe rose into the air and sent a torrent of flame at Natsu.

Swallowing the blast like a liquid, Natsu grinned and wiped his mouth. "Boys, girls, I fight anyone!" He shot toward her.

"What the hell is this guy?" Phoebe raised her brow.

"No!" Finn leapt and tackled Natsu before he reached her, driving him into the street below.

The blonde watched as the battle escalated and shook her head, turning to the raven-haired man who leaned against a lamppost. "Could you go and stop him, Gray?"

"Be my guest, Lucy, I'm not stepping him." He turned to the blonde and stretched out. "It's nice to have someone else knock some sense into his head for once."

Happy darted around as he couldn't decide what to eat next. Swooping down to a woman near a store, he landed on her shoulder and licked her cheek. "Ew! What kinda candy is this?" He jerked back and the woman ran off.

"You know they're not _actually_ made of candy, right?" Jake raised his brow as he stood near a car. "Well, their hair is, but they are people."

"Ah, dog!" Happy backed up in surprise.

"That's racist."

Lucy closed her eyes as Finn punched Natsu, causing him to crash into a building and looked around in a panic. "Erza!" She ran toward the redhead who kissed a house shaped like a cake passionately.

"I don't know what they'd call this, but I'm gonna marry you." Erza looked at the edifice with half-lidded eyes. "I love you." Blushing furiously, she bit into the house and buried her face into it.

"Uh …" Lucy raised her brow and Erza turned to her with frosting all over her face.

"I'm not sharing!" She donned her Adamantine Armour, placing her shield around her as she began to disrobe.

"Erza!"

"What is it?" She popped her head above the shield. Lucy pointed behind her and she turned, seeing children running away from her in a panic. "Ah, I'll eat them later." She returned to making out with the building.

"Erza, that's a person's house and these people aren't really made of candy!" Lucy frowned.

"Really?"

"No and we could really get in trouble once the cops arrive."

"Oh." Erza donned her normal attire. Wiping the cream off her face, she chuckled and rubbed her neck. "Sorry."

"Well, don't apologize; just stop Natsu from wrecking the place!"

"Right." Erza looked around and saw Natsu knock Finn onto a truck with a kick. "Natsu!" The mage ignored her. "Natsu!" She growled as he continued fighting. Drawing her sword, she javelined it at him and it landed on the wall near his head.

"Hey, what was that for!?" Natsu yelled.

"You've gotta stop fighting or –,"

Finn punched Natsu down and stepped on his head. "I will destroy you!" He unsheathed his sword.

"Stop!" Lucy screamed at the top of her lungs and drew the attention of the people around her. Laughing uneasily at all the attention, she cleared her throat and walked toward Finn. "Stop, we're not your enemies."

"Then why were you destroying buildings?" He turned to her.

"I'm sorry about my friends." She winced and gestured around. "I'm Lucy Heartfillia," she gestured to the raven-haired man, "that's Gray Fullbuster, that's Erza Scarlet, the cat's Happy and that guy you're stepping on is Natsu Dragneel. We're wizards from the Fairy Tail guild in Fiore and we accepted a mission request sent to us by Princess Bubblegum –,"

"Heh, bubblebutt." Natsu snickered and Finn stomped on his head. "Get off!" He jumped to his feet, knocking him aside.

Lucy huffed. "She sent a request for us to hunt down demons in Ooo and that's why we're here."

"Hunting demons? But that's my job." Finn's expression fell.

"Wait, you were chasing down that demon?" Natsu raised his brow

"Yeah, that was until you butted in and killed it before I could ask questions!" Finn growled at Natsu and butted heads with him.

"I hope you understand that we didn't mean any harm." Lucy smiled pleadingly.

Looking into her eyes, he nodded uneasily. "Okay, fine." He kicked Natsu aside.

"That's it!" Natsu moved to punch him when Erza quickly backhanded him and caused him to fall over.

"Now, please take us to your queen so that we may properly introduce ourselves." Erza sheathed her sword.

* * *

METAL CLANKED and glass smashed as Finn, Phoebe, Jake, Natsu, Erza, Gray, Lucy and Happy waited in the hall outside Bonnie's lab. Sharing confused looks, Lucy and Gray winced as a crash came and the door flung open. Jumping out of the room, Bonnie slammed the door shut and breathed heavily as she leaned against it.

"Heh, sorry." She adjusted her glasses. "An experiment got a little … wild." She straightened her lab coat. "Hey, I'm Princess Bubblegum, but people call me Bonnie." She shook the mages' hands.

"I thought you were the queen of this kingdom." Erza's brows crossed in confusion.

"Well, I'm ruling the kingdom, but I'm not a queen." She greeted Natsu whose eyes dilated in excitement.

"Whoa, a pink hot chick made of candy? I'll eat you out!" Erza punched him and knocked him over.

"Forgive my friend, he's … he needs help."

"Okay …?" Bonnie raised her brow.

"It's great to meet you, your highness." Lucy smiled. "We're from Fairy Tail."

"Oh, so you got my request." Bonnie's face lit up.

"How could you hire people to hunt demons? That's my job!" Finn whined.

"Well, yes, but I thought you could use a little help." Bonnie turned to him.

"So, what's your situation?" Gray crossed his arms. "Is there like a horde of demons or something?"

"Oh man, why did I agree to go on this mission?" Happy clasped his face in fear.

"Don't worry, little guy; it won't be so bad." Jake offered a smile to the feline and noticed him calm down. "You'll just be ripped to shreds is all." Happy yelped.

"The mission's simple; I just need you to go all around Ooo and round up as many demons as you can." Bonnie smiled and the mages' mouths fell agape.

"You want us to search for demons throughout an entire continent?" Gray raised his brow. "That could take years."

"Not with this virile hound dog of a man." Bonnie gestured to Natsu. "I've heard his nose could smell creatures miles away."

"Yes, but it could still take long." Erza sifted her mind. "How many demons are we supposed to capture?"

"Well, as many as he sees fit." Bonnie pointed at Finn. "And he's never satisfied till all the _bad guys_ are taken down." She giggled and he frowned.

"Hmm, I don't know if I like this idea." Gray cocked his neck. "How much are you paying us? You kept that off the request."

"Oh, must've forgotten that." She stroked her chin. "How's a million jewel a piece sound?"

"What?" Natsu's brow rose.

"Hey, you don't pay me!" Finn pouted.

"Oh, Finn." Bonnie touched his shoulder sensually. "Do I need to?" She looked him in the eyes.

"Mmm-mm." He shook his head.

"Good." She smirked.

"Oh, so when she does it." Phoebe muttered and looked away.

"So, how does that sound?" Bonnie turned to the mages.

"Well, I guess we'll have to think about it –,"

"We'll take it!" Natsu cut Erza off.

* * *

NATSU GAGGED and held his mouth tightly as he leaned against a tree in the forest in the Candy Kingdom outskirts. Finn and Phoebe looked at him with curiosity as the mages walked onward. "Uh, you sure your friend's okay?" Finn turned to them.

"Yeah, Dragon Slayers just get a lil motion sick when they get on modes of transport; it's no big deal." Gray pocketed his hands and continued walking.

"Dragon Slayers? I've slayed dragons before and nobody's given me any titles."

"Not our dragons." Happy flew past him. "You'd get roasted alive."

"Relax, Finn, at least they call you a hero." Phoebe placed a hand on Finn's shoulder.

"It's still not fair." Finn walked on and didn't notice her frown. "I've slayed demons, dragons, trolls – I've saved a lotta people and all they call me is a hero?"

"The hero thing is a little overrated." Gray shrugged.

"Well, at least we're … good Samaritans, right?" Lucy raised her brow.

"Only if there's money involved from what I've heard about you guys." Jake walked past her.

"Wait, you knew about them?" Finn turned to him.

"Yeah, I mean, why'd you think I didn't attack them when I saw 'em? I read the papers."

"I read too." Finn pouted. "I've just been a little busy."

"No, you don't read." Phoebe chuckled.

"Well, who needs books when you're a swordsman!?" Finn drew his sword and held it forward.

"Now that's the spirit!" Erza unsheathed her blade and stood beside him. She looked at the setting sun dramatically and turned to Natsu. "Join us, Natsu."

"I think I'm gonna p –," He held his mouth and quickly vomited behind a tree.

"Are you sure he's okay?" Finn looked at him with worry.

"He'll be fine." Erza draped her arm over his shoulder. "Now onward, fellow warrior!"

Finn cleared his throat and looked around uneasily as he was pressed against her breast. Diverting his thoughts, he turned to Gray. "Hey, if you're wizards, what kinda magic do you use?"

"I use Ice Make magic." The mage held his hands forth, a fist in a palm, and parted them, creating an ice sword that floated.

"I use Requip Magic." Erza donned her Flight Armour, making Finn drool at her cheetah print top.

"Oh, come on." Phoebe facepalmed.

"I'm a Celestial Wizard and I summon spirits with my gate keys." Lucy tapped her key bag on her belt. "I've had a little trouble with summoning them for a while though."

"What happened?" Finn turned to her.

"It's a long story."

"And I'm a Fire Wizard!" Natsu leapt in front of them and fire burst from his body.

"Mathematical." Finn's face lit up with glee.

Brushing his thumb past his nose, the mage grinned and turned to him. "So, what are you then? You're not a wizard."

"No, but I collect lotta magical stuff." Finn smirked. "These gauntlets have a lotta weapons like bombs and grappler knuckles, I have a buncha swords in my backpack, my boots make me run fast and this amulet protects me from all the elements."

"So, you're basically like Erza?" Natsu raised his brow.

"No, no, I'm no –,"

"Well, whatever, you sound like someone I wanna fight! What do ya say, huh? One round before we keep going?"

"You're on!" Finn brandished his sword.

"Wait!" Lucy raised her hand and looked around.

"Oh come on, can't I have a little fun?" Natsu raised his brow.

"Shh! Listen." Lucy frowned and looked around. A man's scream came weakly from the forest. "You heard that?"

"Let's have a look." Erza moved past her.

Moving out of the pathway and into the bushes, the group manoeuvred through the trees and followed the sound. Sniffing the air, Natsu gestured for them to follow him and he led them to a slope. Poking their heads through the leaves, they looked down in surprise.

"What the hell?" Gray frowned.

A black humanoid demon with red markings over its skin stood before a Candy citizen who sat against a tree. The man breathed haggardly as wounds littered his body that was clad in tattered clothes. He suddenly began to convulse, his eyes sinking into his skull as his body buckled and broke down into pieces. The shattered flesh and bone shrank down, flew toward the beast and disappeared.

"Whoa, what just happened?" Phoebe's brow rose.

"I don't know, but I'm gonna stop it." Finn leapt onto the slope.

Sliding down the grass, he drew out Bloodsoak and flipped over, drawing the attention of the demon as he landed before it. The being fired black energy at him from its forehead and he dodged. Looking to the sky, the beast growled as the mages came down and surrounded it.

The demon shot at the opponents around it and jumped back as Finn swung at it. Sidestepping from a fireball sent by Natsu to its left, the beast gave the mage an uppercut that flung him onto a tree. Phoebe punched at it from the right and it kicked her back.

"Ice Make: Lance!" Gray sent a volley of lances at the demon. The being fired at the projectiles, melting them and hit Gray in the gut, sending him into a nearby stream.

Erza slashed at the demon's head and gut with her two swords, each attack missing as it jumped back and headbutted her. Enlarging his arm, Jake smacked the demon off its feet and lunged toward it with a punch. The being shot him out of the sky and flipped to its feet, eyeing the mages who lay around him in pain as it steadied itself.

Fishing out a key, Lucy ran toward the stream and watched as Finn engaged the demon. "Please work, please work – please work!" She held it before her. "Open Gate of the Scorpion: Scorpio!" She turned the key and opened an energy magic circle that released a spirit with red and white hair in the form of a black teenager.

"Wicked!" Scorpio fired a stream of sand out of a cannon on its back that knocked the demon over.

Natsu launched into the air. "Fire Dragon Roar!" He spat fire on the being and it writhed in pain.

Turning to the mage, the beast tried to fire at him when Finn quickly threw a sword into its chest. Wobbling about, the beast spat out blood and fell over. Watching the flames rise, Natsu and Lucy moved up to the creature, the blonde squinting as she watched it burn.

"Is it dead?" Happy flew over to them.

"Yeah." Lucy stood up when something caught her eye. "What's this?" She ran past the demon and picked up a round jar with a torn strap on it.

"What's that?" Gray came up to her.

"I dunno."

The guys crowded around Lucy and Erza took the jar from her. "Hmm, this must've been where the man was sucked in." She squinted at it. "There're markings on it."

"Wait a minute." Finn frowned and took the vessel from her. "I think I've seen this before.


End file.
